It means that TL1 saved your data in a file format that TL2 doesn't recognise. So you can't open your old TL1 file with TL2. If you reinstall TL1, you would be open to open your old data, but TL1 is about 10 years old, no longer available and would not have all the latest eBay prices or settings.

You'd need to create an account in TL2, and then start creatings listings from scratch.